This invention relates generally to vehicle headlamps and particularly to those employing discharge lamp bulbs as light sources. More particularly, the invention deals with a vehicle headlamp system having provisions for aiming the headlamp assembly both horizontally and vertically and retaining the same in the proper position. Still more particularly, the invention pertains to such an aimable vehicle headlamp system featuring improved electrical connection between the discharge lamp assembly and an electric lighting circuit assembly.
Discharge lamps, notably including metal halide lamps, are finding ever increasing acceptance as light sources of vehicular headlamps. There has, however, been a problem left unsolved in use of discharge lamps for vehicular headlamp applications. The discharge lamp units of a headlamp system need electric lighting circuits including a voltage booster for providing a high voltage required for each discharge lamp bulb to glow by an electric discharge between the pair of electrodes opposed to each other within the bulb. The lighting circuits themselves are powered by the battery that is customarily mounted on the motor vehicle.
Conventionally, the lighting circuits have been positioned considerable distances away from the aimable discharge lamp assemblies. Elongate cables or cords have been used for electrically connecting the lighting circuits to the lamp assemblies. The present applicant objects to the use of such elongate cables that conduct currents at high voltages. One reason for this objection is the possibility of current leakage from the cables. Another reason is that the elongate cables are very easy to produce electric noise. Such sources of noise production should be eliminated, or at least reduced to an absolute minimum, as today's vehicles, passenger cars in particular, are furnished with an increasing number of electric or electronic appliances.
For all these reasons there have been strong demands from the automobile industry for the advent of headlamp systems that employ discharge lamps with no, or minimum lengths of, high voltage supply cables.